Even in the best of economic times, funding for infrastructure maintenance, repair and rehabilitation is never adequate. As infrastructure in the United States continues to age, the funding deficit to simply maintain the existing bridges will continue to soar. Due to the inadequacy of capital allocated for infrastructure repair and rehabilitation, new, more durable construction materials with potentially longer service lives are being explored as a means of narrowing the financial deficit. One such material is fiber reinforced polymer matrix composites (FRP). By replacing conventional bridge component structural materials (i.e.; reinforced concrete and steel) with FRP, which has a higher strength to weight ratio, bridges can achieve a significant reduction in dead load weight. Bridges that have experienced substructure and superstructure deterioration can undergo a superstructure replacement with FRP rather than be subjected to the traditional load posting (vehicular load restrictions). Through reducing the bridge dead load without compromising bridge strength, original design live loads can be maintained. In order for these new bridge superstructure components to be readily accepted as viable construction materials, quick and effective means of monitoring them for degradation and overall structural health must be established and standardized. One of the most promising methods of achieving this is through the use of thermal infrared (TIR). A slight increase in temperature above ambient will allow for adequate inspection of large sections of bridge decking for detection of debonded areas between FRP components. This paper illustrates the successes and challenges of using TIR for this purpose, both in the laboratory and in field investigations. Areas for future work and improvements will be suggested.

Date Published: 1 April 2003
PDF: 11 pages
Proc. SPIE 5073, Thermosense XXV, (1 April 2003); doi: 10.1117/12.499021

Published in SPIE Proceedings Vol. 5073:
Thermosense XXV
K. Elliott Cramer; Xavier P. Maldague, Editor(s)